Murray, goes in the same direction:—“The pure blacks,” he says, “are not so healthy as the half-castes. Always the children of two half-castes will be healthier and stronger than either the children of blacks or the children of a black and a half-caste. When a half-caste man and woman marry, they generally have a large and vigorous family. I could point to half a dozen such.”[1666] These statements of highly competent persons are, I think, quite sufficient to disprove M. Broca’s hypothesis. They show that, if a mixed race is almost wanting in certain parts of Australia, this does not depend upon physiological conditions of the kind suggested. It should be remembered that the sexual intercourse of Europeans with savage women is most commonly transitory and accidental, and frequently takes place with prostitutes or licentious women, who are generally known to be sterile. And, even when the white settler takes a native’s daughter to live with him under his own roof as a wife or a concubine, and accustoms her to a half-civilized manner of living, her unfruitfulness[1667] may be owing to quite another cause than the mixture of blood. Mr. Darwin has shown that changed conditions of life have an especial power of acting injuriously on the reproductive system. Thus animals, as also plants, when removed from their natural conditions, are often rendered in some degree infertile or completely barren, even when the conditions have not been greatly changed. And this failure of animals to breed under confinement cannot, at least to any considerable extent, depend upon a failure in their sexual instincts. “Numerous cases,” says Mr. Darwin, “have been given of various animals which couple freely under confinement, but never conceive; or, if they conceive and produce young, these are fewer in number than is natural to the species.”[1668] It is reasonable to suppose that savage man, when he moves into more civilized conditions, is subject to the same law. Indeed, statements have been reported to me, which tend to show that the indigenous women at the Polynesian missionary stations have become less fruitful than they were in their native state. As to the alleged sterility of crosses between the European and Australian races, it should be observed that the rarity of mongrels in certain parts of Australia is more or less owing to the natives themselves habitually destroying the half-castes.[1669] The Rev. A. Meyer states that, in the Encounter Bay tribe, “nearly all the children of European fathers used to be put to death;”[1670] whilst, among the Narrinyeri, about one-half of the half-caste infants fell victims to the jealousy of their mothers’ husbands.[1671] But with regard to the West Australian aborigines in the neighbourhood of Fremantle, the Rev. J. Johnston writes that he does not think it has been the custom there to destroy the half-caste illegitimate offspring of black women, as he never heard of such a thing,—a fact which may